Time division multiplex radio system



July 14, 1953 H. M. VEAUX 2,645,770

TIME DIVISION MULTIPLEX RADIO SYSTEM Filed Feb. 15, 1949 2 Sheets-Sheetl TERM/NA TING RES/571411165 IGN L S OUR ZE AMPLIFIER SIG/VAL M ,5SOURCE PLF R SWITCH RECEIVER TERM/NA TING AMPl/F EA RESIST/MICE mTERM/NAT/AIG RES/STANCE DELAY AMPLIFIER 4 m 5 sou/m5 0F lsr /DELAYL//VE\AMPLlF/E m kCE/VER E A R sY/v. sw/rcw a sw/rgu FIG. 5.

CHARACTER/377C R5575 r ANCE RECEIVER 0614 Y 1. [NE INVENTOR H M VEAl/XBY ATTORNEY I g July 14, 1953 H. M. VEAUX 2,645,

' TIME DIVISION MULTIPLEX RADIO SYSTEM Filed Feb. 15, 1949 2Sheets-Sheet 2 v LWARACI'ER/Jf/C Y REJIJI'AIVCE 1 Emy1.//v RECEIVER FIG.6.

TELEPHONE RECE V51? suase'r E m J F I G 7 TRANSM/I'I'EK DIV/DESFREGl/'A/CY DELAY L/NE' B) 4 Sl/VU50/DA1. SOURCE CHARACI'EP/SI'AC R5513rAA/CE SINUS OIDAL $0l/RCE BY 2 y.

ATTORNEY Patented July 14,

TL iMEi 'W iS Q iMi H EXR W HenriMau rice Veaux', saiht-Leu la-rl oretirence 1 r j Febriiai y li in France FebruafflfiIMS" I V V f scram? (o1.an -204x: V

1' The present invention cohce'riis' th''usje of one or severaldela'y'lines associated witlia switching device. The invention is inract'an extension of the application ofth system whioh' is the object ofmy 'c'opending patent application, Serial N02 54,395, filed October 14,1948, now abandoned,

under the title: Use of a DelaylLin e WithMu'ltiple Tapp'ing's asaMean's for the stor ng and Alterae tion of Duration of Signal'sfland'my depending.

application, Ser. No.- 5 ,39 filedOctober 14, 1948',

now'P'a't. No. 2,585,058, granted ebruary 12, 1952,

under the title: systemrcr connecting a'Radio Station "to aTelephony',NetWorl'Utilizing the Same Frequency Band r theTwoffDirections'f of Transmission," and mycopending explication, Se;rial gNo. 58;705; filediNbvrhbffi, 1948,1under the y em fer i iefi f ewere of Siginals.

The first mentioned app icati n giv'e s principain-anew realisation oftheis'y'stem described in French Patent No. 932,934 invi'e'w'ot reducingthe time taken by a-teleplionicphototelegraphic or televisiontransmission, I 2;

The first object of the present invention consists in determining withan the desirable accuracy theconditions ot operation and of the use ofthe embodiment-disclosed inliifench Patent No. 932,934 in whichtheinscriptionon an iconoscope mosaic is replaced hythe temporary storingof t signals nade anli e Fig-r 1 isa schematic diagram ofia known plextransmitting circuit I Fig. 2 is a schematic diagram ot a twqchanneljreceiving circuit embodying thejnvention;

Fig. 3 is a schematic diagram of a three channel receiving circuitembodying, the invention;

Fi 4 is a schematic-diagram of a modified I form of transmittingcircuit;

Fig. 5 is a schematic diagramt'oi a modified.

form of receiving circuit} I 1 Fig.6 is a schematicdiagramofa'jeommemial telephone system embodying the mv'emmny Fig. 7 isaschen'iaticfdiagrairfof a known arrangement for altering fth'e durationof signals)" Fig. 8 is a schematic diagram illustrating the extension ofthe arrangement of Fig. 7 and incorporating the inventiqfiiifandfl Fig;-9 is a schematior'ep'res tation of an electronic switch which maybeusdwith the invention. I

Fig. 1 corresponds to the simple case of two transmissions coming fromtwo signal sources S1 and S2 (telephony signals, for example) i it doesnot differ in anyway, in its'principle, from cor'itrolsrthe"alternativeunlocking of the two channels"andtransmitsettheoutput at E synchromsing signals useful'for the reception.

Hi "The inventron concerns the reception as shown bythegenerakindicationsmf Fig. 2; it consists inseparatingtheftrainsbelonging alternately toone and" tlieother'channel and in switchingthem"to thecorresponding'terminal receivers di w rectlyand indirectlythrough a delay line; each train'beiongfii achanne'l' arrives on'the"terminarreceiver'directly andthrough a delay line;

thetrai'rrcoming-frbm the" delay line'gives a rep'etition'ofthetrai'nfdirectly received and, in 20*thisway, fillsirrthe"tree-interval between two original consecutive trains:

Figure 2 and'tfic following numerical values given-by way offinfcrmationwill removeall ambiguityre'gardirrg-the real object of the inven-' 25,,tion; -The signal" trains delivered after detect-ion by theradioelectric receiver R supply at'point D r the delay lines Lr and Lewhich terminate on the-characteristic resistances-Z1 an'd'Zz; -Re--''ce' iver B1 of-channel' 'l is alternatively fed from camplifiers A'1'andAH driven respectively at ponds- Hand Kp-a similar-process ieeds there--' ceiver R2 of a switch C alternatelyunlocks'theamplifiersAi, Affi,A: and A2'distributedin-two*gronpsm'r, A'z) and (A"1, Azl; ;,.thecadenceof theswitehing-is phase controlled,

starting from the separating synchronising signals of the trainsswitched over at S at the out put of-R. The-operating mechanism isestablishedfeis iollowsyswi'tch-c (Fig. 1) alternately ;ufilocksamp1ifiers"'n and A2 according to a periodicity or 10' milliseconds; thealternative trains which each-have a-ydnration of -10millisecondsaferes'tored at-D (Fig. 2) at the output of receiver R; thedelayof lines Liand L2 in the ent ire' band" tobe" transmitted (3,000c./s-.- in

commerciaitele honyi is fixed at the value of 10 milliseconds; thebeginning-of an impulse trainbelongingto channel-l enters simultaneouslyat Hand "L theamplifiers- A; and A's; at the same ,;morn-ent',switcir'clefle'cts' the nnblocking of A'l' arid 1&"2 and the blocking of-A"1- and Azi for 10* mill seconds-the train of channel-i supplies'd-i--- rectl'y and through A'r-the corresponding receiver 5 R1,-whilst-the preceding train of channel 2', pre- Figure 1 of FrenchPatentNo. 932,934 adapted vvidfis ystiird ln' e dur n preceding anneis:Aswitch C tin-- locks alternately the two amplifiers A1 and suppliedfrom two sources Sr and S2; the signals v picked up at' the" input of"amplifier A are "thus "--ma-de up ot'eqnal alternative trains comingfrom Stand S2; a'som'ce of'synchronising signals O'- To sum up, one sametrain of channel Iis V alternatively received by feeding processesstarting from points H and K; .the damping in L1 is compensated by anequivalent increase of the amplification of A"1 with respect to A1; theresults are similar for channel 2.

The suppression of the sending of thephase.

signals of switches C and C brings about a considerable simplification;a well known technique enables this phase adjustment to be maintainedwithout difficulty for a very long. time, longer than the time taken forthe longest conversation; a control at the receiving end of the signalspicked up on channels I and 2 enables the phase of switch C to beregulated at any. moment. The system can be adapted, naturally, tosingle side band transmission systems. With a view to avoidingcross-talk between channels due t reverberation effects in propagation,successive trains at 8 M./S., for example, can be slightly shortened atthe transmitting end,without aifecting the receiving arrangement. Thesystem can be adapted to the case of more than two channels.

Figure 3 corresponds to the receiving arrangement for three channels.The trains belonging successively to the three channels have, forexample, a duration of 6 milliseconds; Figure 3 only gives the parts ofa single channel I supplying the receiver R1. The delays of lines L1 andLi' are fixed at 6 milliseconds. A same train directly received throughA1 is successively repeated through Ai and A"1 the amplifications ofwhich are regulated so as to compensate the dampings or attenuation. I

The system can be used for the case of a wire or cable transmission. Ina multiplex transmission with numerous channels, on a coaxial cable, forexample, the numerous telephonic channels can be grouped two by two,three by three, etc. The same switches C and C can be utilised at bothends of the cable to control simultaneously the blocking and unblockingoperations on the various groups. A permanent coupling may ensure thephase adjustment of the switches C and C.

In phototelegraphy, the signal trains obtained at the sending end(Fig; 1) tone and the other.

channel starting from the phototelegraphy ap paratus S1 and S2 can beregulated to the duration of one revolution of the'cylinder bearing theimages to be transmitted; the'lines Ll and L2 of Fig. 2 are regulatedwith a delay corresponding to this value. In television, the signaltrains can be adapted to the durationof transmission of a line or of animage.

The first-mentioned application Ser. No. 54,395 gives principally a newrealisation of the system described in French Patent No. 932,934 in viewof reducing the band of frequencies occupied by a telephonic.photo-telegraphic or television transmission. The second object of thepresent invention consists in determining with all the desirableaccuracy the conditions of operation and utilisation of the embodimentof the above mentioned system in which the time conversion as from aninscription and a reading of the signals on the mosaic of an iconoscopeare replaced by the temporary storing of the signals in a delay linewith multiple tappings and by the reading of these same signals at thedesired speed by a rapid exploration of the tappings of the delay line.In short, the invention consists in:

(1) Picking up, at the transmitting end, signal trains of the sameduration separated by free intervals and regularly distributing thesignals of each train over the time which separates the beginning of twosuccessive trains, in such a way as to obtain prolonged trains;

(2) Reestablishing, at the receiving end, each prolonged train to theduration of the initial train and repeating each train thusreestablished so as to suppress or to reduce any unwanted intervals inthe transmission.

(3) Utilising for the time conversions delay lines with multipletappings associated with switches and, for the repetitions, delay linesgiving at their output a repetition of the input signals.

Figs. 4 and 5 and the following numerical data given by way ofinformation will remove all ambiguity regarding the real object of theinvention:

At the transmitting end (Fig. 4), the source of signals S. supplies themultiple tapped delay line L terminated on its characteristic resistanceZ and associated with switch C, the exploration of whose tappings in thedirection of the arrow give time converted signals at output B, throughthe filter amplifier F. For a total delay of line 0 and an explorationfrequency of the switch at a rate of N1 turns per second. every signalfrom the source S of frequency N gives, at the output, a frequencysignal:

. F=N (1-0N1) each prolonged train presents a duration N1 7 andcorresponds to a period of signals delivered by S of duration (Ti-0).

At the receiving end (Fig. 5), the radioelectric receiver R feeds adelay line L of the same delay 0 as that of line L of the transmittingend. The tappings made on L through switch C exploring in the directionof the arrow, effect a reestablishment of the prolonged trains to theiroriginal duration, the trains obtained feed the receiver R1 through afilter amplifier F, either directly by means of amplifier A, orindirectly through one or several delay lines (Fig. 5 gives only oneindirect feeding system L1) which sup ply the desiredrepetitionsintended to fill in the free intervals.

The sending of phasing signals during the exploring movements ofswitches C and C is not indispensable in practice as is shown in theexplanations given above with regard to Figs. 1 and 2. v

The following numerical data, given by way of information, concern acommercial telephony transmission. The band of signals supplied by S(200 to 3,000 C./S.) is reduced at the output at B to the limitsGOO-1,500). The duration of the delay of line L has a value of 0:10milliseconds. With respect to (1) we have i. e. T==10 millisecondsfA'n'uinberbr equal to 80 on line L-'. is suitable. H stored at the outputof F havea"durat oiidand': are separated by intervals of ofduratio layline L1, with a delay efsuppiies sig" tended to fill in the freeintervals.

propagation over the delay lines 'ca'n bfe coin'p'e sated by a variableamplification efiectfed iiij chronism. The compensation ca also 'b otained between successive lines scanned difierently at the transmittingend andat the rece'iV-. ing end: a train scanned at L,fstartin'g gro n{oer-1 minal I is subjected from the beginning" to the end to analternation compensated by Ia gain during the scanning at the receivingn'dfoll'owparts shown in Figs. 4 and 5 are; with the exception of thesource of signals"S,ithe, radioelefctric receiver R and the receiver Ri;,'installed; a'tfthe same phase (link center .to 'the"telephdnefnet workfor telephony). 'I'hej p nising controlof"s'witchesd an efiected from acommonsource f I p j The present invention'comprises'a combination ofparts with a view principally't reducingthe- 7 frequency band occupiedbye radioelectric'trans's mission of the above mentioned devicesandoifthe devices described in the above mentioned application, Serial No.54,394;

Fig. 6 shows the general Slit-ill of cial telephone systemassociatedwith a 1:45 phone network. The subscriber of the networkpossesses a micro-telephone orisub sefls a "df ciated with a receiverR1." The swltclrci I ciated with the delay line Li gives byrot'at n inthe direction of arrow f1 the conversionof: dura-- tion (multiplicationby'two' of the ffrequencie's)"" of the signals emanating fromfSi'If" flThe signals emanatingffromD n' the amplifier F have a frequericy band'"riiited fetween 400 and 6,000 cycles per'sec'ondfor Eirequency bandoccupied by the'signalsiernanating' from s1 and com rised between 1:values 2007 and 3,000 cycles per secondi "For divls'ionby 4 of thefrequency of the signals emanatnigfromf D inverse conversion is]produced, switch C2 associated with line Lzlan obtained in E which areused "for he I tion of the radio electric transmitter; tlifsigfi nalsoccupying the frequency band. between'fl00 and 1,500 cycles per second;The following data given as'fan i v, determine a modeof operationnccephis {or the direction of the transmitterfTh switclrqi comprisestappings' distributed 1 the" quarter of a circumference and assoc ated lto anode 2, a. signal: train. ota dnrationi-of; 51.75;

justed'atsuch-avalue that: 1 a

h H t oneactiverevolution for every two). K

6. milliseconds e resentm a signal train. transmitted in -mm-i-lliseconds'"from:source S At thestartfof the scanningof' Glenterminal L fer instance; the scanning of C2 begins on terminal I -in-thedirection of arrow f2. The speed erscanning of Cebe'ing the same asthatof Crab-'8 rate orone revolution in 20 rn-illiseconds (i. 'esNi*='50-t./seca the total delay o of line L2" is ad that; is 0 :15milliseconds- There isferz plored inl this-way at each revolution ofvCir in 20 :millis.

. seconds a train of 5 milliseconds emanating from.

D; i. e'.,= a portion representing halfofnthexsigi-r nals supplied bysource S1. A suitable definition. ottl iesignalssinthe output E (at arate 018,000 impulses for a frequency or 3',000)'.is obtained by:

The weakening of the, signals fi' thy r of a switch c2 having soelectrodes (80.

impulses for one rotation of, C2 in 20 milliseconds). i The condition ofphase in theascanr. ning of Cr and C2 does notpresent any difiiculty;

the same supply source provides the scanning motion of Ci and C2.

mg line In practical-working conmfiidns,=the line La. Each train of 20milliseconds lying in a 1i R1 by directly traversing thebranch of theam-v plifier A and indirectly a braincliof'adelaylin'e' L4 giving adelay of 10 milliseconds. The switch C: which rotates at a speed of 50revolutions per secondscans the electrodes fed from. tappings providedon the delay line L3 and giving a delay. of 10 milliseconds. Thetappings on line L3 feed" 80 electrodes of C3 distributed according tothe upper half circle. A train of signals of 20 milliseconds emanating.from Rand occupying the. frequency band limited between and 1,500cycles per second givesatthe output of C3 a train of 10 millisecondsduration which traverses directl'y A and is halved through 104' forfeeding: Rlin a continuous manner. Feedbacks. towards R1 or signals fromSi along the route RLIRI are avoided by blocking amplifier A" under thein'-. fluence of currents collected through :a detector D by means ofcurrents delivered by the amplifier filter F. It is alsopossible tooperate the blocking as from D of any one of the devices of the chain"of transmission emanating from R (alsoextinction or switching ofi orblocking of 1 the beam of the switch C3). With the distribution ofelectrodes adopted,- the switches C102 and C2 rotate at the same speed.It is possible to adopt a uniform distributton ofthe electrodes ofswitches-C1 and 03- provided the speeds of rotation are modified and'='that there is established unused timeinte'rval's" between two rotationscorresponding to an effec;

tlve scanning (rota'tio'n'of C1 at a speed of '20j0 revolutions 'persecond comprising an effective rotation forv every four rotations;therotation' of Q clam speed of 100 revolutions 'persec'ond "w v All thedevices shown in Fig. \.6 being, with the? exceptionpiSn R1 andR,arranged ilrthe sa pl celin 1t en m l' cond tion. o exp gi atip (li k cetre ,orgthe ie ep enetwq tklat e ed...

,{ustmnt and the regulation of phase will be made in the most favourableconditions.

The arrangement of Fig. 6 is adapted to atime multiplex transmissionwith, for instance, four channels according to my copending arrangementof Fig. 3 of the patent application, Ser. No. 54,394. Each one of thesources S1 and S2 corresponds according to the arrangement describedabove. to two transmission channels interleaved in time.

My copending patent application, Ser. No. 58,705, mentions in connectionwith Fig. 12, reproduced in the present application as Fig. 7, a systemcomprising in a reciprocal working, a delay line associated with aswitch C and a sinusoidal source S. Let be the total delay of the lineand let N represent the frequency of the source and let N1 be the numberof revolutions per second of the switch. There is then obtained for arotation in the direction of arrow f1 and for a working comprisingimpulse actions on the various electrodes of the switch, output currentsrepresenting respectively the following frequencies:

There is disposed, for a revolution of C made in an interval of time i Nl impulses representing a number of periods which come out insi in aninterval oftime and from S2 in an interval of time there resulttherefrom the values of F1 and F2 given above. The impulsive emissionsare made preferably by means of an electronic beam suitably modulatedfrom the signals outgoing from S. For a speed N1, such that 1 Nr-F thefrequency F1 is theoretically infinite. This result is obvious since inthis case there is concentrated in a space theoretically nil the impulses corresponding to one revolution of the switch.

The present invention comprises an extension of the system of alterationof duration of signals represented in Fig. 7 The principal of thisgen.-' eralisation is given in Fig. 8. A source of signals S feeds aline Ll having a total delay 61 termi nated on its characteristicimpedance Z1. I A switch moving in the direction of arrow f1 closessuccessively contacts (ll) (n-n) established respectively betweenconsecutive cells of line L1 and of line L2 having a total delay 02. Ateach closing of contact there is sent an impulse between thecorresponding cells of L2, this impulse is propagated in bothdirections; in the case in which the speed of scanning of the contactsvery great with respect to 02 andln there is a transfer over line In ofsignals stored in line L1 andthe alteration of duration of the signalcollected in S: is madein the ratio Fig. 9 represents an electronicswitch which can be used for these operations. At the back oi the switchthere is provided n electrodes connected to tappings on line L2; theelectrodes connected to tappings of L1 are arranged along a ring andeach comprises an opening. There is a modulation of the beam F sent atconstant intensity and moved along a circular scanning path during thepassage through the electrodes connected to the tapping of L1; theconjugated scanning of the electrode bearing the same number. provides atransfer of signals from line L1 to line L2.

The invention is not limited to the examples above described which havebeen given merely as examples of embodiments of the invention and not aslimiting its scope.

What is claimed is:

1. A communication system comprising a transmitter, a receiver, means atthe transmitter for producing a signal to be transmitted, means forselecting and transmitting portions of said signal at regularly repeatedtime intervals, means at the receiver for intercepting the transmittedsignal, signal reproducing means, means for feeding the signal directlyfrom said intercepting means to said reproducing means, a delay line,means for feeding said signal from said intercepting' means, throughsaid delay line to said reproducing means, the delay of said line beingsuch that the continuity of signals is preserved at said reproducingmeans by the alternate receipt of direct signals and signals from saiddelay line, and means for compensating for the attenuation of thesignals passing through said delay line.

2. A communication system comprising a transmitter, a receiver, aplurality of means at the transmitter for producing independent signals,switch means for successively selecting and transmitting portions ofeach signal in interleaving relation with portions of the other signals,means controlled by said switch means, for transmitting a synchronizingsignal, means at the receiver for intercepting said signals, separatereproducing means at the receiver for each signal, a delay line meansfor each reproducing means, means connected with each reproducing meansfor feeding signals from said intercepting means directly to saidreproducing means, means connected with each reproducing means forfeeding signals to said reproducing means through said delay line means,and synchronizing means connected between said signal intercepting meansand said signal feeding means for blocking said feeding means exceptduring intervals of time which contain the signals for the particularreproducing means.

3. A system according to claim 2, in which the feeding means includesamplifiers.

4. A system, according to claim 3, in which the gain of each amplifierassociated with a delay line means is adjusted to compensate forattenuation in the delay line means.

5. A communication system comprising a transmitter, a receiver, means atthe transmitter for producing-a signal to be transmitted, means forselecting and transmitting successive portions of said signal at apredetermined rate of regularly 9 repeated time intervals, means at thereceiver for intercepting the transmitted portions of said signal andpresenting them at the proper rate for reproduction, signal reproducingmeans, means for feeding the intercepted portions of said signal fromsaid intercepting means directly to said reproducing means, a delayline, means for feeding the intercepted portions of said signalfrom saidintercepting means through said delay line to said reproducing means,the delay of said line being such that the continuity of signals ispreserved at said reproducing means by the alternate receipt of directsignals and signals from said delay line, and means for compensating forthe attenuation of the signals passing through said delay line.

HENRI MAURICE VEAUX.

Numb er Number Name Date Campbell May 29, 1928 French May 29, 1928 CorpeNov. 12, 1929 Blumlein Sept; 12, 1939 White Jan. 9, 1940 Wilson Q. Feb.17, 1942 Corderman June 4, 1946 Lawson Jan. 14, 1947 FOREIGN PATENTSCountry Date Great Britain Oct. 14, 1926

